Control linkage

ABSTRACT

Systems and methods for implementing control linkages that may be employed to produce synchronous motion in two adjacent controlled devices controlled by a common input. In one example implementation, a semi-rigid modified constant velocity (CV) joint control linkage may be provided that is laterally self-stabilizing. The modified constant velocity CV joint control linkage may include an input push rod assembly that is self-aligning, deflectable and of an adjustable length. The CV joint may be configured with a central cage that is allowed to skew to allow for alignment of the controlled devices.

This patent application is a continuation of co-pending U.S. patentapplication Ser. No. 11/003,788, entitled “Control Linkage”, filed onDec. 2, 2004 which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to control linkages, and moreparticularly to control linkages configured to produce synchronousmotion in adjacent controllable devices.

2. Background

Conjoined flight control surfaces are often employed on aircraft. Oneexample of conjoined flight control surfaces are dual swept elevatorsurfaces found at the top of the vertical stabilizer of many “T-tail”aircraft. These dual elevator surfaces are hinged control surfacesadjacently mounted at the trailing edge of the horizontal stabilizer,and act in unison to provide control of the aircraft about the pitchaxis. In many T-tail aircraft, dual swept elevator surfaces are actuatedby control horns that take the form of swing arms individually connectedto adjustable threaded rod ends of a common (bifurcated) pitch controllink. During flight maneuvers, torsional forces tend to cause a rockingmotion (aeroelastic) of the horizontal stabilizer relative to thevertical stabilizer. This rocking motion tends to induce torque on thebi-furcated pitch control link. This torque will impart a lateraldeflection into the control horns and produce differential elevatormotion, which can result in a aerodynamically unstable condition, i.e.,causing buzz or flutter of the control surfaces.

In many T-tail aircraft, the elevator control horns and bifurcated pitchcontrol link are laterally stabilized by a torque knee linkage attachedto the fixed vertical stabilizer in order to address the instabilitythat can result from the twisting rocking motion of the horizontalstabilizer relative to the vertical stabilizer. In such aircraft, thebifurcated pitch control link is nominally stabilized by a forward hingeattachment to a rigidly mounted control lever. Lateral spacing of theindividual rod ends provides enough moment couple to allow differentialelevator travel and a resultant lateral swing in the pitch control link.The torque knee linkage is attached to the elevator pitch control linkto restrain the observed lateral looseness.

Use of the torque knee stabilizing linkage addresses the looseness ofthe elevator control linkage path in non-flying “static” condition.However, in flight the aeroelastic motion exists between the horizontaland vertical stabilizers tends to induce additional loads and in turncreates a source of wear in the stabilizing system. Experience has shownthat wear is induced by the aeroelastic dynamics in the torque kneelinkage results in elevator trailing edge freeplay and lateral motion inthe control linkages. This wear often necessitates replacement of thetorque knee linkage, and requires that a routine maintenance program beimplemented to monitor the condition of the torque knee linkage.

SUMMARY OF THE INVENTION

Disclosed herein are systems and methods for implementing controllinkages that may be employed to produce synchronous motion (e.g.,synchronous rotation) in two adjacent devices (e.g., control surfaces)controlled by a common input. In one embodiment, the disclosed controllinkages may be advantageously implemented with any apparatus or devicehaving two adjacent controllable devices that need individual alignmentbut share a single control input. Example implementations include, butare not limited to, aircraft control surfaces such as adjacent elevatorpanels, adjacent flap panels, adjacent slats, adjacent spoilers,adjacent airbrakes, etc. Other example implementations include, but arenot limited to, boat or ship control surfaces (e.g., adjacent trimvanes), active automotive suspension and steering systems (e.g., bodyroll induced and/or bounce induced tire camber changes), surface shipstabilizer surfaces, submarine control surfaces, etc. Advantagouesly,the disclosed control linkages may be installed as original equipment ofa control system, or may be retrofitted to an existing control system byreplacing one or more components of the original system with componentsof the disclosed control linkages.

In one embodiment, disclosed is control linkage that employs asemi-rigid modified constant velocity (CV) joint and push rod linkage toreplace the elevator control horns, input control link (e.g.,bi-furcated pitch control link) and torque knee components that aretraditionally employed to actuate dual swept elevator surfaces of T-tailaircraft. The modified CV joint linkage mechanism may be installed asoriginal equipment on a new aircraft, or may be retrofitted to apreviously installed elevator system of an existing aircraft. In eithercase, the lateral rigidity of the modified CV joint may be used tosubstantially eliminate the need for a torque knee auxiliary linkage tothe vertical stabilizer structure, and to lock the two surface hingelines together using the CV joint to transmit rotational motion betweenskewed shafts. Advantageously, the disclosed control linkage islaterally self-stabilizing and may be implemented to substantiallyeliminate the aeroelastic motion feedback path and loads experiencedwith traditional configurations.

The disclosed modified CV joint linkage mechanism may also beimplemented to address alignment and/or rigging requirements for twoadjacent control surfaces that need individual alignment but share asingle control input for common deployment, and may be implemented inone embodiment to provide adjustability that advantageously reduces therigging requirements for aligning adjacent devices (e.g., tail surfacesof a T-tail aircraft) and other components. For example, in the case ofadjacent elevator surfaces of a T-tail aircraft, elevator control andindividual trailing edge rigging capabilities may be combined. In thisregard, the CV joint of the control linkage may be configured so thatthe midplane of the central cage of the CV joint is allowed to be skewedrelative to the nominal CV joint centerline (e.g., a line connecting thecenter-points of two universal joints of the CV joint) for surfacetrailing edge alignment through differential motion, and to allow jointcompensation for manufacturing variation of the airframe and linkagecomponents without shimming. For example, in one embodiment, the centralcage of the CV joint may be capable of maximum skew of plus or minusabout 2.5 degrees to the nominal rotational axis. For example, thedisclosed control linkage may be provided with a push rod linkage thatis provided with an optional push rod deflection mechanism in the formof an adjustable eccentric circular cam contained within an elongatedopening or slotted cavity in the aft portion of the rod. The adjustableeccentric cam may be employed to deflect the push rod about a roddeflection pivot point to rig the surface trailing edges. With thisexemplary configuration, the mechanism may be used to skew the centralcage of the CV joint and to rack the surface hinge lines withdifferential motion. When the surface trailing edges align, the cam maybe configured to be locked in position to hold the rod deflection andthe skewed cage position.

The disclosed modified CV joint configuration disclosed hereinadvantageously combines the ability of a conventional CV joint tofaithfully transmit rotational motion (synchronous motion) with anadjustability that allows for phase shifting of the adjacent hinge lineshafts and synchronization of adjacent controllable devices (e.g., twoadjacent elevator surface trailing edges) so as to provide adifferential motion rigging capability. Additionally, the combination ofone rigid yoke axle and one semi-rigid self-aligning yoke axle may beused to allow the modified joint installation to accommodatemanufacturing variation of the rotating shaft locations (e.g., hingeline shaft locations) and angular variation of the universal joint(yoke) axles, e.g., to allow a standardized modified CV joint linkagemechanism to be provided and used for retrofitting different aircraftwithout requiring customization, shimming, etc. The combination of amodified CV joint and a deflectable push rod allows for substantiallyfull adjustability or rigging of two adjacent control surfaces (e.g.,two adjacent elevator surface trailing edges) with a single common inputlink while also compensating for a variety of manufacturing andinstallation variables, while at the same time requiring no shims. Whenimplemented as a control linkage for dual adjacent elevator surfaces,the disclosed CV joint installation provides for synchronous rigging tomatch the cockpit controls and isolates the control system linkage fromaeroelastic deflections and loads.

In one respect, disclosed herein is a control assembly for controllingtwo adjacent controllable devices, including: a first rotational jointconfigured for coupling to a first one of the controllable devices; asecond rotational joint configured for coupling to a second one of thecontrollable devices; and a cross-connection coupled between the firstand second rotational joints.

In another respect, disclosed herein is a control linkage mechanism forproducing synchronous motion in two adjacent elevator surfaces of aT-tail aircraft, including: a rigid universal joint yoke assemblyconfigured for coupling to control a first one of the adjacent elevatorsurfaces; a semi-rigid universal joint yoke assembly configured forcoupling to control a second one of the adjacent elevator surfaces; acentral cage coupled between the rigid universal joint yoke assembly andthe semi-rigid universal joint yoke assembly; and an input push rodassembly having a first end coupled to the central cage and a selfaligning second end configured for coupling to a control input device.

In another respect, disclosed herein is a dual elevator system for anaircraft having a vertical stabilizer and a horizontal stabilizerattached to the vertical stabilizer, the dual elevator system including:a first elevator assembly, the first elevator assembly having a firstelevator surface and a first elevator hinge, the first elevator hingebeing rotatably attached to the horizontal stabilizer of the aircraft; asecond elevator assembly, the second elevator assembly having a secondelevator surface and a second elevator hinge, the second elevator hingebeing rotatably attached to the horizontal stabilizer of the aircraft;and a modified CV joint control linkage mechanism. The modified CV jointcontrol linkage mechanism may include: a rigid universal joint yokeassembly having a yoke axle coupled to the first elevator hinge, asemi-rigid universal yoke assembly having a yoke axle coupled to thesecond elevator hinge, a central cage coupled between the rigiduniversal joint yoke assembly and the semi-rigid universal joint yokeassembly, the central cage being coupled at a first end to the rigiduniversal joint yoke assembly with a rigid hinge axle and being coupledat second end to the rigid universal joint yoke assembly with asemi-rigid hinge axle, and an input push rod assembly having a first endcoupled to the central cage and a self-aligning second end coupled to acontrol lever, the control lever being fixedly attached to the verticalstabilizer of the aircraft.

In another respect, disclosed herein is a control assembly for producingsynchronous motion in two adjacent controllable devices, including: afirst yoke means for rotatably coupling to a first one of thecontrollable devices; a second yoke means for rotatably coupling to asecond one of the controllable devices; and a yoke connection means forrotatably coupling each of the first and second yoke means together inlaterally spaced relationship.

In another respect, disclosed herein is a method for inducingsynchronous motion of two adjacent controllable devices, including:providing a first rotational joint coupled to a first one of thecontrollable devices, and a second rotational joint coupled to a secondone of the controllable devices, the first and second rotational jointsbeing coupled together by a cross-connection; and inducing thesynchronous motion in the first and second controllable devices inresponse to a single input control motion received in the crossconnection; wherein the synchronous motion is induced by providingcontrol motion to the first controllable device through the firstrotational joint, and providing control motion to the secondcontrollable device to the second controllable device through the secondrotational joint.

In another respect, disclosed herein is a method of installing amodified CV joint control linkage mechanism in an existing dual elevatorsystem of an aircraft having a vertical stabilizer and a horizontalstabilizer attached to the vertical stabilizer, the method including:providing a modified CV joint control linkage mechanism that includes arigid universal joint yoke assembly, a semi-rigid universal yokeassembly, a central cage coupled between the rigid universal joint yokeassembly and the semi-rigid universal joint yoke assembly, the centralcage being coupled at a first end to the rigid universal joint yokeassembly with a rigid hinge axle and being coupled at second end to therigid universal joint yoke assembly with a semi-rigid hinge axle, and aninput push rod assembly having a first end coupled to the central cageand a self-aligning second end. The method may include the steps of:attaching the rigid universal joint yoke assembly to a first elevatorhinge of a first elevator assembly of the elevator system, the firstelevator hinge being rotatably attached to the horizontal stabilizer ofthe aircraft; attaching the semi-rigid universal yoke assembly to asecond elevator hinge of a second elevator assembly of the elevatorsystem, the second elevator hinge being rotatably attached to thehorizontal stabilizer of the aircraft; and attaching the self-aligningsecond end of the input push rod to a control lever of the elevatorassembly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified oblique view of a dual elevator system accordingto one exemplary embodiment of the disclosed systems and methods.

FIG. 2A is a simplified oblique view of a dual elevator system accordingto one exemplary embodiment of the disclosed systems and methods.

FIG. 2B is a simplified oblique view of a dual elevator system accordingto one exemplary embodiment of the disclosed systems and methods.

FIG. 3 is an exploded oblique view of a dual elevator system accordingto one exemplary embodiment of the disclosed systems and methods.

FIG. 4 is an exploded oblique view of a rigid yoke assembly according toone exemplary embodiment of the disclosed systems and methods.

FIG. 5 is an exploded oblique view of a semi-rigid yoke assemblyaccording to one exemplary embodiment of the disclosed systems andmethods.

FIG. 6 is an exploded oblique view of a central cage assembly accordingto one exemplary embodiment of the disclosed systems and methods.

FIG. 7 is an exploded oblique view of an input push rod assemblyaccording to one exemplary embodiment of the disclosed systems andmethods.

FIG. 8 is an exploded oblique view of selected forward portioncomponents of an input push rod assembly according to one exemplaryembodiment of the disclosed systems and methods.

FIG. 9 is an exploded oblique view of selected aft portion components ofan input push rod assembly according to one exemplary embodiment of thedisclosed systems and methods.

FIG. 10 is an exploded oblique view of a CV joint assembly according toone exemplary embodiment of the disclosed systems and methods.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

FIG. 1 is a simplified oblique view of a dual elevator system 100 thatincludes dual swept elevator surfaces 102 and 104 that are mechanicallycoupled by elevator hinges 103 and 105 to components of a controllinkage that is configured according to one exemplary embodiment of thedisclosed systems and methods. In this embodiment, dual elevator system100 is shown as an elevator system configured for use in the tailassembly of a T-tail aircraft (e.g., Beech Model 400, Beech Model 390,etc.). However, as described elsewhere herein, the control linkages ofthe disclosed systems and methods may be configured for use in otherimplementations.

Still referring to FIG. 1, components of the control linkage of theillustrated exemplary embodiment include a deflectable input push rodassembly 112 that is mechanically coupled to rigid universal joint yokeassembly 110 and semi-rigid universal joint yoke assembly 108 byconstant velocity (CV) joint cage 114. Rigid universal joint yokeassembly 110 has a rotating axis that acts as a pure hinge and lateralanchor to CV joint cage 114 and that maintains a fixed distance fromhinge line 103. Semi-rigid universal joint yoke assembly 108 is anchoredto CV joint cage 114 by a rotating axis that has self-aligning capacityrelative to CV joint cage 114 and that maintains a fixed distance fromhinge line 105.

Elevator hinges 103 and 105 are rotatably anchored to elevator hingefitting 106 in a manner that allows hinges 103 and 105 to hinge orrotate about their respective axes in the direction of arrows 107 so asto impart up and down motion to trailing edges of elevator surfaces 102and 104 in the direction of arrows 109. Elevator hinge fitting 106 isrigidly attached to a stationary component of the tail assembly (e.g.,horizontal stabilizer 150). Cross bolt connections 130 and 132 areprovided to couple elevator hinges 103 and 105 to rigid yoke assembly110 and semi-rigid yoke assembly 108, respectively. Rigid yoke assembly110, semi-rigid yoke assembly 108 and CV joint cage 114 together definea CV joint assembly.

In the exemplary embodiment of FIG. 1, the CV joint assembly (i.e.,formed by rigid yoke assembly 110, semi-rigid yoke assembly 108 and CVjoint cage 114) is laterally anchored by cross bolt connection 132between elevator hinge 103 and rigid yoke assembly 110. In thisembodiment, the lateral rigidity of the CV joint assembly advantageouslyeliminates the need for a torque knee auxiliary linkage to the verticalstabilizer structure 152. At the same time, the CV joint assembly actsto lock together the two elevator hinge lines by virtue of the abilityof the CV joint assembly to transmit rotational motion between skewedshafts for synchronous surface deflection control. It will be understoodthat a CV joint assembly may be configured in any other suitable mannerto achieve the self-aligning benefits of the disclosed systems andmethods. In this regard, the disclosed CV joint assembly may beimplemented with self-aligning capability using a CV cage and acombination of a rigid or non-self-aligning joint with a semi-rigid orself aligning joint.

Referring now to FIGS. 2A and 2B, the CV joint assembly may be furtherconfigured to allow central cage 114 to skew from the nominal positionto allow for surface trailing edge alignment of elevator surfaces 102and 104, and to give the added benefit of allowing the CV joint assemblyto be used to compensate for manufacturing variation of the airframe andlinkage components without any shimming. In this regard, skew of centralcage 114 may be accomplished using any suitable methodology and/orconfiguration. As shown for the illustrated embodiment, the CV jointcentral cage 114 may be skewed at the cage hinge connection to the aftend of the input push rod assembly 112, and input push rod assembly 112may be configured to be deflectable in opposing directions perpendicularto the longitudinal axis of push rod assembly 112 about rod deflectionpivot point 296 as indicated in dashed outline and by opposing arrows120 a and 122 a. In FIGS. 2A and 2B, a portion of elevator hinge fitting106 has been hidden to allow cage 114 and rigid yoke assembly 110 to beseen.

As shown in FIGS. 2A and 2B, deflection or displacement of the body ofpush rod assembly 112 in the directions of arrows 120 a and 122 a causescage 114 to skew and translates to movement of trailing edges 142 and140 of respective elevator surfaces 104 and 102 in opposite directionsas indicated by arrows 120 b, 120 c, 122 b and 122 c (i.e., displacementor deflection of the body of push rod assembly 112 in the direction ofarrow 120 a results in movement of trailing edges of elevator surfaces104 and 102 in the directions of arrows 120 b and 120 c respectively,and deflection of the body of push rod assembly 112 in the direction ofarrow 122 a results in movement of trailing edges of elevator surfaces104 and 102 in the directions of arrows 122 b and 122 c respectively).Arrows 120 f and 122 f show movement of elevator hinge 105 about itsrespective axis, and arrows 120 g and 122 g show corresponding movementof elevator hinge 103 about its respective axis.

Still referring to FIGS. 2A and 2B, arrow 120 d shows movement ofsemi-rigid yoke assembly 108 in response to deflection of the body ofpush rod assembly 112 in the direction of arrow 120 a, and arrow 122 dshows movement of semi-rigid yoke assembly 108 in response to deflectionof the body of push rod assembly 112 in the direction of arrow 122 a.Arrow 120 e shows movement of rigid yoke assembly 110 in response todeflection of the body of push rod assembly 112 in the direction ofarrow 120 a, and arrow 122 e shows movement of rigid yoke assembly 110in response to deflection of the body of push rod assembly 112 in thedirection of arrow 122 a. Arrows 120 h and 122 h show skew movement ofcage 114 corresponding to respective displacement or deflection of thebody of push rod assembly 112 in the direction of respective arrows 120a and 122 a.

During the adjustment of the push rod assembly, the rigid yoke assembly110 and the semi-rigid yoke assembly 108 provide support for the ends ofthe central cage 114. Simultaneously the yokes 108 & 110 are rotating inopposite directions (differentially) with their associated surface hinge105 & 103 respectively. The rigid yoke assembly 110 will tilt andstabilize the central cage 114 via the rigid bearing axle. The resultingmisalignment of the central cage 114 with the semi-rigid yoke 108 isallowed by the self-aligning capabilities of the roller bearing withinthe semi-rigid yoke 108. The capacity of the of the semi-rigid yoke 108to compensate for misalignment gives this linkage the added capacity tocompensate for the manufacturing and assembly tolerances of theseconjoined surfaces and components without resorting to shimming orcustom fitting upon installation.

In the illustrated embodiment of FIGS. 1 and 2A and 2B, rigid universaljoint yoke assembly 110 located at one end of the CV joint assemblysubstantially eliminates lateral looseness of the control linkage, andtherefore eliminates the need for a torque knee linkage forstabilization. Furthermore, input control rod assembly 112 may beprovided with a self-aligning capability that substantially eliminatesthe aeroelastic torsional loading from the stabilizer structure hingelines to the control system components (e.g., yokes, cage and push rodassembly) and therefore acts to improve durability of the controllinkage.

Deflection of the body of input push rod assembly 112 of FIGS. 1 and 2Aand 2B may be accomplished using any suitable configuration and/ormethodology, and any given portion or portions of the body of input pushrod assembly 112 may be deflected that causes cage 114 to skew. Forexample, as described and illustrated further herein with respect toFIGS. 3-10, input push rod assembly 112 may be used to rig the elevatorsurface trailing edges 140 and 142 by using an adjustable and lockableeccentric cam shaft 720 that may be contained within the aft portion 182of the rod to deflect the input push rod assembly 112 and skew the cage114 so as to rack the surface hinge lines with differential motion. Whenthe surface trailing edges 140 and 142 align, input push rod assembly112 may be locked in deflected position by locking eccentric cam shaft720 in position to hold the skewed position of cage 114. Further, theforward end 180 of input push rod assembly 112 may be configured to beadjustable in length and to have a self-aligning capability (e.g., byvirtue spherical roller bearing rod end and a turnbuckle lengthadjustment) that breaks the torsional deflection load path of thecurrent control linkage between the vertical stabilizer and horizontalstabilizer through the pitch control lever 184 to the elevator mountedcontrol horns (not shown). Advantageously, this torsional load pathdisconnect may be provided to eliminate aggravating control input fromthe aeroelastic dynamic motions while still providing a substantiallycompletely stabilized elevator control linkage.

As described above, the ability to skew or move the axis of the CV jointcage 114 from being parallel to the joint axis may be used for purposesof control surface trailing edge alignment. Deflecting and locking theaft end of the pitch control push rod (e.g., in one embodiment by up toabout ±2.5 degrees from a “normal” non-deflected or straightconfiguration) may be used to skew or rotate the cage 114 through thehinge connection axle 370 of FIG. 3 relative to the nominal CV jointcenterline (shown as line 330 of FIG. 3). This bent configuration allowsfor alignment of the elevator trailing edges 140 and 142. As illustratedin FIG. 3, the forward end 180 of the input control push rod assembly112 may be configured with a self-aligning length adjustment mechanismin the form of turnbuckle assembly 310 and threaded self-aligning rodend bearing 712 (shown in FIG. 7) that allows for push rod lengthadjustment and synchronous rigging of both elevator surfaces 102 and104.

FIGS. 3 through 10 illustrate in greater detail components of a dualelevator system 100 that includes a control linkage that is configuredwith a modified CV joint control linkage mechanism according to oneexemplary embodiment of the disclosed systems and methods. In theillustrated embodiment, the modified CV joint linkage mechanism includesfour mechanical elements working in conjunction to transform a commandinput into synchronous rotation of two control surface hinge lines(i.e., of elevator hinges 103 and 105). These four mechanical elementsinclude two bearing yoke assemblies 110 and 108, a central cage 114 withan integral input clevis 315, and a command input push rod assembly 112.As illustrated, the two “U” shaped bearing yoke assemblies 110 and 108are each attached at a right angle to respective control surface hingelines of elevator hinges 103 and 105 by cross-bolts 130 and 132extending through openings provided in the uprights of the respective“U” shaped yoke assembly 110 or 108 to secure the control surface hingeline torque tube structure 103 or 10S between the uprights. In thismanner, each attachment cross-bolt 130 and 132 serves as an axle of auniversal joint mechanism. The second axle of each universal joint isestablished by bearings located in openings of the cross member of the“U” shape of each yoke assembly 110 and 108. As shown, a centerline 330of the CV joint assembly (i.e., formed by rigid yoke assembly 110,semi-rigid yoke assembly 108 and CV joint cage 114) is defined by a lineextending between the mid-point of the crossbolt axle of yoke assembly110 and the mid-point of the crossbolt axle of yoke assembly 108.

As described further below for this exemplary embodiment, the centralbearing of rigid yoke assembly 110 is a doubled bearing pack (406 & 408)that acts to produce a rigid axle that is coplanar with, and at a rightangle to, the cross-bolt axle 130 and the control surface hinge line103. In this exemplary embodiment, the central bearing of semi-rigidyoke assembly 108 is a self-aligning roller bearing 508 that is orientedin “U” of the yoke assembly 108 in the same manner as the centralbearing 406/408 of rigid yoke assembly 110, and gives semi-rigid yokeassembly 108 a self-aligning capacity. However, it will be understoodthat a semi-rigid yoke assembly may be configured with any othersuitable type of self-aligning bearing or feature in the practice of thedisclosed systems and methods, e.g., self aligning spherical bearing,etc.

Still referring to the exemplary embodiment of FIGS. 3-10, central cage114 is a solid “T” shaped component with devises 317 and 319 at theextremes of the cross member and clevis 315 at the upright leg. Thewidth between the axles of cross member devises 317 and 319 is the sameas the nominal distance between the mid-points of the installed yokes110 and 108. Clevis 315 of the upright member of the “T” is coplanarwith the other clevis axles and serves as a hinge axis for the aft end182 of input push rod assembly 112. Input push rod assembly 112 isarticulated laterally in the aft portion and adjustable in length with athreaded self-aligning roller rod end bearing and turnbuckle assembly310 at forward end 180. The articulated aft rod end 182 is configuredwith a doubled bearing pack that forms rigid hinge axle 704 that mateswith the middle clevis 315 of central cage 114. The forwardself-aligning roller rod end 180 may be attached to a clevis of acontrol input device such as an existing control lever (not shown inFIG. 3).

By cantilevering cage 114 to one side of the joint axis and using oneself-aligning bearing 508 and one rigid bearing pack 406 to join cage114 to the universal joint yoke assemblies 108 and 110 introduces twodegrees of freedom within the CV joint linkage mechanism. These twodegrees of freedom are a 1) lateral freedom and 2) fore and aft rockingfreedom from the “normal” resting position of the CV joint geometry.These added freedoms of motion compensate for the shaft hinge linepositional tolerance and allows cage 114 to misalign from the normalposition parallel to the joint axis. This freedom to misalign cage 114may be implemented to give the desired ability to shift the relationshipof shafts of elevator hinges 103 and 105 by differential rotation. Inthe embodiment of FIGS. 3-10, alignment of cage 114 may be controlled bya rigid hinge axle connection 704 to the aft end 182 of the commandinput push rod. Push rod assembly 112 may be bent at a pivot axle (e.g.,eccentric cam shaft 720) located in the aft portion of the push rodassembly. The deflection angle of push rod assembly 112 acts to twistcage 114 by substantially the same angle around the rigid control yokeuniversal joint axle (e.g., rigid bearing pack 406/408). The twist ofcage 114 is accommodated by tilt within the self-aligning bearing 508 ofsemi-rigid control yoke 108 and acts to produce differential rotation ofthe surface hinge lines of elevator hinges 103 and 105. The resultingdifferential rotation of the control surfaces 102 and 103 allowsalignment of the surface trailing edges 140 and 142. The lateralstability of the disclosed modified CV joint linkage mechanismsubstantially eliminates the adverse deflections and loads ofaeroelastic motion within the control system components and thereforeenhances the system durability.

As shown in FIG. 4, rigid yoke assembly 110 includes a “U” shaped yokebody 400 with yoke axles formed by rigid pair of cross-bolt bearings 402and 404 (that are received in yoke openings 401 and 403 defined in yokeuprights 420 and 422) that are configured for receiving cross bolt 132of dual elevator system 100. Rigid yoke assembly 110 also includes aspaced pair of cage hinge bearings 406 and 408 received in yoke opening405 to form a bearing pack axle. As shown, spaced pair of hinge bearings406 and 408 are separated by bearing spacer 410. This bearing pack axleacts as a hinge axle for central cage 114 and transfers the controlinput forces from cage 114 to the upper cross-bolt bearing pair 402 and404. The yoke axles formed by cage hinge bearings 406 and 408 provide CVjoint position restraint through the hinge line attachment to structure.Although one exemplary embodiment of a rigid rotational joint in theform of rigid yoke assembly 110 is described above, it will beunderstood that any other rigid rotational joint configuration may beemployed that is suitable for providing rotation in a single planerelative to cage 114 or other cross connection device, e.g., lateralrotational motion relative to cage 114 or other cross connection device.

As shown in FIG. 5, semi-rigid yoke assembly 108 includes a “U” shapedyoke body 500 with yoke axles formed by rigid pair of cross-boltbearings 502 and 504 (that are received in yoke openings 501 and 503defined in yoke uprights 520 and 522) that are configured for receivingcross bolt 130 of dual elevator system 100. Semi-rigid yoke assembly 108also includes a self-aligning roller bearing 508 received in yokeopening 505. In one exemplary embodiment, self-aligning roller bearing508 may be received in yoke opening 505 and configured with thecapability of tilting or pivoting (i.e., as indicated by arrows 590 and592) with yoke body 500 about axis 594 (e.g., provided by fastener bolt1004 of FIG. 10) relative to central cage 114 in an amount less than orequal to about ¼ degree relative to yoke body 500 (but alternatively maybe less than about ¼ degree or more than about ¼ degree in otherembodiments). The allowable tilt range may be enlarged for a givenapplication by giving up some range hinge rotation motion. Uninstalled,self-aligning roller bearing 508 may have a tilt capacity of about 10degrees in one embodiment.

The self-aligning capacity of roller bearing 508 allows positional andangular variation (i.e., misalignment) between the surface hinge linecross-bolt axle 130 and central cage 114 which is fixed by the rigidyoke assembly 110 to the surface hinge line cross bolt axle 132. In oneembodiment, this angular variation may be described as the accumulatedtolerances of the elevator hinge fitting and torque tube structures. Thecombined cross-bolt rotational freedom and bearing self-alignmentfreedom of yoke assembly 108 also allows longitudinal axis of cage 114to be moved from being parallel to CV joint assembly centerline 330.This freedom of movement allows for a rotational offset or rigging ofthe two surface hinge lines of respective elevator hinges 103 and 105 ofelevator system 100, e.g., by deflecting input push rod assembly 112 soas to rotate cage 114 in a manner as described elsewhere herein.Although one exemplary embodiment of a semi-rigid rotational joint inthe form of semi-rigid yoke assembly 108 is described above, it will beunderstood that any other semi-rigid rotational joint configuration maybe employed that is suitable for providing rotational motion in multipleplanes relative to cage 114 or other cross connection device, e.g.,including lateral rotational motion relative to cage 114 or other crossconnection device.

FIG. 6 shows an exploded oblique view of central cage assembly 114 thatprovides a rigid position control between the self-aligning bearing ofsemi-rigid yoke assembly 108 and the axles of rigid yoke assembly 110.As illustrated, middle input clevis 315 includes openings 614 forreceiving two input clevis bushings 602 configured to form a rigid axlefor coupling to aft end 182 of input push rod assembly 112 in a mannerfurther described herein. Further, each of devises 317 and 319 includerespective openings 610 and 612 for receiving clevis bushings 604 or 606configured to form an axle for coupling to one or yoke assemblies 110 or108. In this exemplary embodiment, input clevis 315 may be used toprovide an angular control of the cage position when attached to theinput push rod assembly 112. The adjustability of cage 114 is controlledby the rigid axle of the input clevis 315 being twisted and then lockedout of the “nominal” position by deflecting the aft portion 182 of thecontrol input push rod assembly 112. Twisting or moving cage 114 indirections so that the longitudinal axis of cage 114 is not parallel tothe centerline 330 of CV joint assembly allows the flexibility of themodified CV joint installation to compensate for accumulated tolerancesof the surface assemblies and hinge assemblies and CV joint elementswithout custom fitting or shimming. Although one exemplary embodiment ofa cross connection in the form of central cage assembly 114 is describedabove, it will be understood that any other cross connectionconfiguration may be employed that is suitable for mechanically couplingand laterally spacing two rotational joints (e.g., rigid and semi-rigidrotational joints) that have laterally-spaced axes of rotation relativeto each other and, in one embodiment, for mechanical coupling to acontrol input device, e.g., via push rod assembly 112 or other controltransmission mechanism suitable for transmitting control motion from acontrol input device to the cross connection.

As shown in FIG. 7, input push rod assembly 112 of this exemplaryembodiment includes a forward end 180 and aft end 182, with at least twodiscrete adjustable features, e.g., input push rod assembly 112 may beconfigured to be laterally articulatable and adjustable in length. Wheninstalled in an aircraft as part of a modified CV joint linkagemechanism, input push rod assembly 112 may be employed to transmitcommand input motion from a control lever mounted on the verticalstabilizer (not shown) to input clevis 315 of central cage 114. Theadjustability of push rod assembly 112 acts to combine the rigging andalignment elements of the modified CV joint linkage mechanism. In thisregard, the ability to laterally deflect push rod assembly 112 in orderto skew central cage 114 provides the modified CV joint linkagemechanism with the capability to align the elevator surface trailingedges 140 and 142 and/or to tolerate any manufacturing variation inangularity of the yoke axes on the control surface hinge line torquetubes 103 and 105. The ability to adjust the length of input push rodassembly 112 may be used to position surface trailing edges 140 and 142during rigging operations.

Referring in more detail to FIG. 7, input push rod assembly 112 may beconfigured to articulate laterally in the aft portion of the assembly,although other portion/s of push rod assembly 112 may be alternativelyor additionally configured to articulate laterally (the advantages ofthe aft lateral articulation include minimizing the angular offset andside thrust loads within the forward self-aligning roller rod endbearing 180). In FIG. 7, aft rod end 182 is shown configured with pivotmember 702 that includes a doubled bearing pack forming rigid hinge axle704 for mating with the input clevis 315 of central cage 114. Rigidhinge axle 704 is configured to be fixed and oriented parallel to thelongitudinal axis of central cage 114 when installed as part of amodified CV joint linkage mechanism.

In the illustrated embodiment of FIG. 7, aft end 182 of push rodassembly 112 also includes a push rod deflection mechanism in the formof a lockable eccentric cam assembly that may be used to deflect the rodassembly 112, e.g., for synchronizing the control surface trailing edges140 and 142. Pivot member 702 includes aft openings 726 configured toreceive rod deflection pivot bolt 722 to form a rod deflection point(e.g., rod deflection pivot point 296 of FIGS. 2A and 2B) and forwardopenings 724 configured to receive lockable eccentric cam drive shaft720 that provides lateral force to laterally articulate or deflect inputpush rod 112 about its rod deflection point. Input push rod assemblyalso includes a push rod body 740 that is configured at its aft end tobe pivotably coupled to pivot member 702 as shown. In this regard, aftend of rod body 740 includes an aft opening 746 configured to receiverod deflection pivot bolt 722 and a forward elongated opening 744configured to receive a crescent shaped cam 728. Once assembled withinelongated opening 744, crescent shaped cam 728 is in position to receiveand mate with lockable eccentric cam drive shaft 720, and may be securedin place by a busing (not shown). FIG. 8 further illustrates elongatedopening 744 and crescent shaped cam 728 that is configured to receivedeccentric cam drive shaft 720. When assembled together the crosssections of the eccentric cam drive shaft 720 and the crescent shapedcam 728 form a circular eccentric cam surface (or eccentricallyrotatable cylinder) that is trapped within the elongated opening 744(i.e., the centerline of drive shaft 720 is offset from the centerlineof the rotatable cylinder so that the circular cam surface has an offcenter axis of rotation within opening 744). Also shown is circularopening 746 and cylindrical bushing 730 that receives rod deflectionpivot bolt 722. FIG. 9 further illustrates pivot member 702 with hingebearing 902 that is received in opening 904 to form rigid hinge axle704. Also shown are lower bearings 908 and 910 that are received inlower openings 724 and 726, and upper bearing 906 that is received inupper opening 726.

When assembled as part of a modified CV joint linkage mechanism,eccentric cam drive shaft 720 may be rotated with the mated crescentshaped cam 728 in relation to elongated opening 744 to selectablydeflect rod assembly 112 about its rod deflection point. In this regard,rod assembly may be bent in dogleg fashion about its rod deflectionpoint in the desired direction by rotating eccentric cam shaft 720 withcam 728 until aft end of rod body 740 pivots about rod deflection pivotbolt 722 and rod assembly 112 is displaced or bent laterally by contactbetween the off-centered outer surface of cam shaft 720 and cam 728 onthe inner surface of elongated opening 744 that corresponds to thedesired direction and amount of displacement. Rod assembly 112 may bestraightened by rotating eccentric cam shaft 720 and cam 728 so that theoff-centered outer surface of cam 728 is aligned symmetrically with theinner surface of elongated opening 744, i.e., in a position such thateccentric cam 728 exerts no lateral deflection force on rod body 740.Locking mechanism components 750 are provided for locking or holdingeccentric cam 720 in desired position of rotation.

It will be understood that a lockable eccentric cam assembly is just oneexample of an optional push rod deflection mechanism that may beprovided in combination with a deflectable push rod assembly. In thisregard, any other form of mechanism or methodology that is suitable fordeflecting one or more portions of a deflectable push rod in order toskew the central cage of an attached CV joint assembly may be employed.For example, a two-piece deflectable push rod assembly may be providedwith a set of overlapping push rod adjustment surfaces (e.g., serratedsurfaces) that may be secured together in variable positions with one ormore fastener/s. In such an alternative embodiment, the surfaces may beunclamped, the push rod deflected laterally, and the surfaces reclampedtogether to hold the push rod in deflected position. Thus, it will beunderstood that any one or more parts of a rod assembly may be bent ordeflected in any manner (e.g., using any suitable mechanism) andgeometrical configuration suitable for causing an attached central cageto skew and translate to movement of first and second adjacentcontrollable devices in opposite directions. In this regard, it is notnecessary that a rod assembly be bent in dogleg fashion about a roddeflection point.

As further shown in FIG. 7, forward end 180 of push rod assembly 112includes a length adjustment mechanism in the form of turnbuckleassembly 310 on forward end of push rod body 740 that engages a threadedself-aligning rod end bearing 712. The self-aligning roller rod end 712may be configured for attachment to a clevis of an existing controllever (not shown) mounted to the vertical stabilizer of a T-tailaircraft. In such an exemplary embodiment, the turnbuckle assembly 310and threaded self-aligning roller rod end bearing 712 may be employed inconjunction with turnbuckle assembly 310 for length adjustment toposition surface trailing edges 140 and 142 during rigging. Theself-aligning nature of forward end 180 of push rod assembly 112 alsotolerates or acts to absorb the motion of lateral deflection adjustmentof rod 112. Advantageously, self-aligning rod end 180 also tolerates orallows aeroelastic “rocking” motions between the horizontal and verticalstabilizers (not shown) through the control linkage system withoutadversely loading or deflecting the linkage. This is becauseself-aligning rod end 180 allows input push rod body 740 to be free torotate with the elevator system and horizontal stabilizer relative tothe vertical stabilizer and pitch control lever clevis (e.g., up toabout 10 degrees rotation in one embodiment) without causingmisalignment in the elevator trailing edge surfaces 140 and 142. Furtheradvantageously, this self aligning ability may be implemented withoutthe presence of additional stabilization for push rod assembly 112,e.g., without a torque knee linkage attached between the push rodassembly and the vertical stabilizer.

FIG. 8 further illustrates components of turnbuckle assembly 310(including turnbuckle adjuster 802) and threaded self-aligning rod endbearing 712 having externally threaded rod 790 that threads intointernally threaded turnbuckle barrel opening 791 defined in front endof turnbuckle adjuster 802. As shown turnbuckle adjuster 802 hasexternally threaded rear end 792 that is threadably received in internalthreaded opening 793 defined in forward end of input push rod body 740.In the illustrated exemplary embodiment, external threads of threadedrod 790 may be rotated in relation to internal threads of turnbucklebarrel opening 791 to selectably lengthen or shorten push rod assembly112.

It will be understood that the illustrated length adjustment mechanismcomponents of turnbuckle assembly 310, threaded self-aligning rod endbearing 712 and input push rod body 740 are exemplary only and that anyother configuration suitable for implementing length adjustment may beemployed, e.g., the forward end of an input push rod body may bealternatively configured as an externally threaded rod that is receivedin an extended internally threaded barrel provided on the rear/aft endof a turnbuckle adjuster (i.e., rather than an externally threaded rearend 792) that is otherwise configured with an internally threadedturnbuckle barrel opening on its front end for receiving externallythreaded rod 790 of a threaded self-aligning rod end bearing 712. It isalso possible that a push rod assembly may be configured with lengthadjustment mechanism/s located in one or more portions of a push rodassembly (e.g., including portions other than the forward push rod end).

It will be understood that a turnbuckle assembly and threadedself-aligning roller rod end bearing are just examples of self-aligningand length adjustment mechanisms that may be provided as part of aninput push rod assembly, and that it is not necessary that both push rodself-alignment and push rod length adjustment features be combined, orto be present at all (e.g., an input push rod may be provided withself-alignment and separate push rod length adjustment mechanisms). Inthis regard, any form of length adjustment mechanism and/or methodologysuitable for adjusting the length of an input push rod assembly may beemployed (e.g., ½ turn thread adjustments on the rod end, overlappedserrated segments in place of the turnbuckle, etc). Furthermore, it isnot necessary that a length adjustment mechanism be located on theforward end of an input push rod assembly, e.g., one or more lengthadjustment mechanism/s may be located at any point forward of an inputpush rod assembly that is suitable for adjusting the length of same.

FIG. 10 shows components of a CV joint assembly 1000 of the exemplaryembodiment of dual elevator system 100 described above in relation toFIGS. 3 through 9. CV joint assembly 1000 includes control yokes 110 and108, and cantilevered central cage 114. Yokes 110 and 108 are eachplanar symmetric with two rigid bearings (402 and 404, 502 and 504) foraccepting respective cross-bolts 132 and 130 through respective controlsurface hinge line torque tube structures 103 and 105. As previouslydescribed, yokes 110 and 108 differ from each other in the type ofcentral bearing employed. Rigid yoke 110 employs two spaced rigid hingebearings 406 and 408 (forming a bearing pack) and acts as the anchor endconnection for central cage 114. Semi-rigid yoke 108 employs aself-aligning roller bearing 508. Cantilevered cage 114 may be a rigidmachining that includes two parallel axes with devises 317 and 319provided for connection to the two yokes 110 and 108 respectively, andhaving a third axis normal to the first two axes with a clevis 315provided for connection to command input push rod assembly 112.

In one embodiment, CV joint assembly 1000 may be sub-assembled bybolting the two yokes 110 and 108 to central cage 114 prior to furtherassembly with other components of a modified CV joint linkage mechanism.As illustrated in FIG. 10, this may be accomplished using yoke fastenerbolts 1002 and 1004 that are received through openings 610 and 612 andcorresponding bushings in respective devises 317 and 319, and that arereceived through openings 405 and 505 and corresponding bearings inrespective yoke assemblies 110 and 108.

Although CV joint assembly 1000 includes a rigid yoke 110 and semi-rigidyoke 108, it will be understood that benefits of the disclosed systemsand methods may be realized using a CV joint assembly configured in thesame manner as CV joint assembly 1000, but including two rigid yokesrather than one rigid and one semi-rigid yoke. For example, a dualelevator system of a T-tail aircraft may be configured with a controllinkage that includes a deflectable input push rod assembly that ismechanically coupled to two rigid universal joint yoke assemblies (i.e.,rather than to a rigid universal joint yoke assembly and a semi-rigiduniversal joint yoke assembly) by a CV joint cage. Such an embodimentmay be realized, for example, by substituting a rigid universal jointyoke assembly for semi-rigid universal joint yoke assembly 108 of dualelevator system 100 of FIGS. 1-3. In such an alternative embodiment,shimming may be required for installation of the control linkage.

Referring again to FIG. 3, a modified CV joint control linkage mechanismmay be retrofitted to an existing T-tail aircraft as follows. CV jointassembly 1000 may be installed as part of the existing dual elevatorsystem of the T-tail aircraft by bolting yoke uprights 420 and 422 topreviously installed hinge line torque tube structure 103 that iscoupled to actuate elevator surface 102, and by bolting yoke uprights520 and 522 to previously installed hinge line torque tube structure 105that is coupled to actuate elevator surface 104. Advantageously,self-aligning bearing 508 of semi-rigid yoke 108 may be used tocompensate for manufacturing variance of the elevator assembly location,the angular variation of attachment cross-bolts 130 and 132, and thewidth variation of the centrally positioned hinge fitting 106. In thisregard, self-aligning bearing 508 of semi-rigid yoke 108 allows yoke 108to be tilted as required to adjust for the accumulated tolerances ofeach specific aircraft installation. Installation of command input pushrod assembly 112 acts to restrain CV joint cage 114 by push rod attachbolt 370 that traps aft rod end bearing pack of rigid hinge axle 704 incentral clevis 315 of cage 114 and laterally fixing the forward push rodend 180 in the clevis of the previously installed existing control leverof the aircraft (not shown). Central cage 114 may be moved or twisted soas to align the surface trailing edges 140 and 142 by deflecting the aftportion of input push rod assembly 112 with the push rod deflectionmechanism (e.g., in the form of lockable eccentric cam assemblypreviously described). The forward portion of input push rod may belength-adjusted using the length adjustment mechanism (e.g., in the formof turnbuckle assembly 310) for “rigging” the control surfaces 102 and104 with the cockpit controls to assure full range of motion.

While the invention may be adaptable to various modifications andalternative forms, specific embodiments have been shown by way ofexample and described herein. However, it should be understood that theinvention is not intended to be limited to the particular formsdisclosed. Rather, the invention is to cover all modifications,equivalents, and alternatives falling within the spirit and scope of theinvention as defined by the appended claims. Moreover, the differentaspects of the disclosed systems and methods may be utilized in variouscombinations and/or independently. Thus, the invention is not limited toonly those combinations shown herein, but rather may include othercombinations.

1. A control assembly for controlling two adjacent controllable devices,comprising: a first rotational joint comprising two first yoke uprightswith a first yoke axle disposed therebetween and a first hinge axleoriented at a right angle to said first yoke axle, said first yoke axlebeing configured for coupling at a right angle to a first one of saidcontrollable devices; a second rotational joint comprising two secondyoke uprights with a second yoke axle disposed therebetween and a secondhinge axle oriented at a right angle to said second yoke axle, saidsecond yoke axle being configured for coupling at a right angle to asecond one of said controllable devices; a cross-connection coupledbetween said first and second hinge axles of said first and secondrotational joints, wherein said cross connection comprises a third hingeaxle between said first and second hinge axles so that said controlassembly produces synchronous motion in said first and secondcontrollable devices in response to a single input control motionreceived at said third hinge axle of said cross connection, and so thatsaid cross-connection is adjustable to produce differential motionbetween said first and second controllable devices; and a self-aligninginput push rod assembly having a first end coupled to said crossconnection at said third hinge axle of said cross connection betweensaid first and second hinge axles, and a second end configured forcoupling to receive said control motion provided by a control inputdevice; wherein said first rotational joint is configured to rotate onlyin a single plane relative to said cross connection; and wherein saidsecond rotational joint is configured to rotate in multiple planesrelative to said cross connection.
 2. The control assembly of claim 1,wherein said first and second rotational joints each comprise auniversal joint yoke assembly.
 3. The control assembly of claim 1,further comprising a push rod deflection mechanism configured tolaterally deflect said input push rod assembly.
 4. The control assemblyof claim 3, wherein said first and second rotational joints eachcomprise a universal joint yoke assembly.
 5. The control assembly ofclaim 1, wherein said first rotational joint is configured for couplingto a first one of said controllable devices that is a control surface ofan aircraft; and wherein said second rotational joint is configured forcoupling to a second one of said controllable devices that is a controlsurface of an aircraft.
 6. The control assembly of claim 5, wherein saidadjacent controllable devices comprise dual adjacent elevator surfacesof a T-tail aircraft.
 7. The control assembly of claim 1, wherein saidfirst yoke axle is configured for coupling at a right angle to a hingeline of said first one of said controllable devices; wherein said secondyoke axle is configured for coupling at a right angle to a hinge line ofsaid second one of said controllable devices; and wherein said hingeline of said first one of said controllable devices is skewed relativeto said hinge line of said second one of said controllable devices.
 8. Acontrol linkage mechanism for producing synchronous motion in twoadjacent elevator surfaces of a T-tail aircraft, comprising: a firstuniversal joint yoke assembly configured for coupling to control a firstone of said adjacent elevator surfaces of a T-tail aircraft that isrotatably attached to a horizontal stabilizer of a tail assembly of saidaircraft; a second universal joint yoke assembly configured for couplingto control a second one of said adjacent elevator surfaces of a T-tailaircraft that is rotatably attached to a horizontal stabilizer of saidtail assembly of said aircraft; a central cage coupled between saidfirst universal joint yoke assembly and said second universal joint yokeassembly; and an input push rod assembly having a first end coupled tosaid central cage and a self aligning second end configured for couplingto a control input device; wherein said first universal joint yokeassembly is configured to rotate only in a single plane relative to saidcentral cage; and wherein said second universal joint yoke assembly isconfigured to rotate in multiple planes relative to said central cage.9. The control linkage mechanism of claim 8, further comprising a pushrod deflection mechanism configured to laterally deflect said input pushrod assembly.
 10. The control linkage mechanism of claim 9, wherein saidpush rod deflection mechanism comprises a lockable eccentric camassembly, said lockable eccentric cam assembly being configured todeflect said input push rod assembly laterally about a rod deflectionpivot point.
 11. The control linkage mechanism of claim 8, wherein saidself aligning second end comprises a self-aligning rod end bearing. 12.The control linkage mechanism of claim 8, wherein said first universaljoint assembly comprises two first yoke uprights with a first yoke axledisposed therebetween and a first hinge axle oriented at a right angleto said first yoke axle; wherein said second universal joint yokeassembly comprises two second yoke uprights with a second yoke axledisposed therebetween and a second hinge axle oriented at a right angleto said second yoke axle; wherein said central cage is coupled betweensaid first hinge axle of said first universal joint yoke assembly andsaid second hinge axle of said second universal joint yoke assembly; andwherein said first universal joint yoke assembly is configured to rotateabout said first hinge axle only in a single plane relative to saidcentral cage; and wherein said second universal joint yoke assembly isconfigured to rotate about said second hinge axle in multiple planesrelative to said central cage.
 13. A control assembly for producingsynchronous motion in two adjacent controllable devices, comprising: afirst means for rotatably coupling to a first one of said controllabledevices; a second means for rotatably coupling to a second one of saidcontrollable devices; and a connection means for rotatably coupling eachof said first and second means together in laterally spacedrelationship; wherein said first means comprises a rigid means forrotating in a single plane relative to said connection means; andwherein said second means comprises a semi-rigid means for rotating inmultiple planes relative to said connection means.
 14. The controlassembly of claim 13, further comprising a self-aligning means fortransmitting control motion from a control input device to saidconnection means.
 15. The control assembly of claim 14, wherein saidself-aligning means for transmitting control motion comprises a push rodassembly; and wherein said control assembly further comprises a meansfor laterally deflecting said push rod assembly.
 16. The controlassembly of claim 13, said first means for rotatably coupling to a firstone of said adjacent controllable devices that is a control surface ofan aircraft; and said second means for rotatably coupling to a secondone of said adjacent controllable devices that is a control surface ofan aircraft.
 17. The control assembly of claim 16, wherein said adjacentcontrollable devices comprise dual adjacent elevator surfaces of aT-tail aircraft; wherein said T-tail aircraft comprises a verticalstabilizer and a horizontal stabilizer supported by said verticalstabilizer; and wherein said dual adjacent elevator surfaces are eachrotatably supported by said horizontal stabilizer.
 18. A method forinducing synchronous motion of two adjacent controllable devices,comprising: providing a first rotational joint comprising two first yokeuprights with a first yoke axle disposed therebetween and a first hingeaxle oriented at a right angle to said first yoke axle, said first yokeaxle being coupled at a right angle to a first one of said controllabledevices; providing a second rotational joint comprising two second yokeuprights with a second yoke axle disposed therebetween and a secondhinge axle oriented at a right angle to said second yoke axle, saidsecond yoke axle being coupled at a right angle to a second one of saidcontrollable devices; providing a cross-connection coupled between saidfirst and second hinge axles of said first and second rotational joints,said cross connection comprising a third hinge axle between said firstand second hinge axles and being adjustable to produce differentialmotion between said first and second controllable devices, said firstrotational joint being configured to rotate only in a single planerelative to said cross connection and said second rotational joint beingconfigured to rotate in multiple planes relative to said crossconnection; providing a self-aligning input push rod assembly having afirst end coupled to said cross connection at said third hinge axlebetween said first and second hinge axles, and a second end configuredfor coupling to receive a single input control motion; and inducing saidsynchronous motion in said first and second controllable devices inresponse to said single input control motion received at said thirdhinge axle of said cross connection; wherein said synchronous motion isinduced by providing control motion to said first controllable devicethrough said first rotational joint, and providing control motion tosaid second controllable device to said second controllable devicethrough said second rotational joint.
 19. The method of claim 18,wherein said first and second rotational joints each comprise auniversal joint yoke assembly.
 20. The method of claim 19, wherein saidfirst rotational joint comprises a rigid universal joint yoke assembly;and wherein said second rotational joint comprises a semi-rigiduniversal joint assembly.
 21. The method of claim 18, wherein said inputpush rod assembly comprises a push rod deflection mechanism configuredto laterally deflect said input push rod assembly.
 22. The method ofclaim 18, wherein said two adjacent controllable devices compriseadjacent control surfaces of an aircraft.
 23. The method of claim 18,wherein said two adjacent controllable devices comprise dual elevatorsurfaces of a T-tail aircraft.
 24. A control linkage mechanism forproducing synchronous motion in two adjacent elevator surfaces of aT-tail aircraft, comprising: a first universal joint yoke assemblyconfigured for coupling to control a first one of said adjacent elevatorsurfaces of said T-tail aircraft; a second universal joint yoke assemblyconfigured for coupling to control a second one of said adjacentelevator surfaces of said T-tail aircraft; a central cage coupledbetween said first universal joint yoke assembly and said seconduniversal joint yoke assembly; an input push rod assembly having a firstend coupled to said central cage and a self aligning second endconfigured for coupling to a control input device; and a push roddeflection mechanism configured to deflect said input push rod assembly;wherein said push rod deflection mechanism comprises a lockableeccentric cam assembly, said lockable eccentric cam assembly beingconfigured to deflect said push rod laterally about a rod deflectionpivot point; wherein said lockable eccentric cam assembly comprises anadjustable eccentric circular cam received within an elongated openingdefined in said push rod.
 25. The control linkage mechanism of claim 24,wherein said first universal joint yoke assembly is configured to rotateonly in a single plane relative to said central cage; and wherein saidsecond universal joint yoke assembly is configured to rotate in multipleplanes relative to said central cage.
 26. A control linkage mechanismfor producing synchronous motion in two adjacent elevator surfaces of aT-tail aircraft, comprising: a first universal joint yoke assemblyconfigured for coupling to control a first one of said adjacent elevatorsurfaces of said T-tail aircraft; a second universal joint yoke assemblyconfigured for coupling to control a second one of said adjacentelevator surfaces of said T-tail aircraft; a central cage coupledbetween said first universal joint yoke assembly and said seconduniversal joint yoke assembly; and an input push rod assembly having afirst end coupled to said central cage and a self aligning second endconfigured for coupling to a control input device; wherein said selfaligning second end comprises a self-aligning rod end bearing.
 27. Thecontrol linkage mechanism of claim 26, wherein said first universaljoint yoke assembly is configured to rotate in a single plane relativeto said central cage; and wherein said second universal joint yokeassembly is configured to rotate in multiple planes relative to saidcentral cage.
 28. A control assembly for controlling two adjacentcontrollable devices, comprising: a first rotational joint comprisingtwo first yoke uprights with a first yoke axle disposed therebetween anda first hinge axle oriented at a right angle to said first yoke axle,said first yoke axle being configured for coupling at a right angle to afirst one of said controllable devices; a second rotational jointcomprising two second yoke uprights with a second yoke axle disposedtherebetween and a second hinge axle oriented at a right angle to saidsecond yoke axle, said second yoke axle being configured for coupling ata right angle to a second one of said controllable devices; across-connection coupled between said first and second hinge axles ofsaid first and second rotational joints, wherein said cross connectioncomprises a third hinge axle between said first and second hinge axlesso that said control assembly produces synchronous motion in said firstand second controllable devices in response to a single input controlmotion received at said third hinge axle of said cross connection, andso that said cross-connection is adjustable to produce differentialmotion between said first and second controllable devices; and aself-aligning input push rod assembly having a first end coupled to saidcross connection at said third hinge axle of said cross connectionbetween said first and second hinge axles, and a second end configuredfor coupling to receive said control motion provided by a control inputdevice; wherein said first hinge axle intersects said cross-connectionat a first end of said cross connection, said first hinge axle beingdisposed at a right angle to said cross connection; and wherein saidsecond hinge axle intersects said cross-connection at a second end ofsaid cross connection, said second hinge axle being disposed at a rightangle to said cross connection.
 29. The control assembly of claim 28,wherein said first rotational joint is configured for coupling to afirst one of said controllable devices that is a control surface of anaircraft; and wherein said second rotational joint is configured forcoupling to a second one of said controllable devices that is a controlsurface of an aircraft.
 30. The control assembly of claim 29, whereinsaid adjacent controllable devices comprise dual adjacent elevatorsurfaces of a T-tail aircraft.
 31. A method for inducing synchronousmotion of two adjacent controllable devices, comprising: providing afirst rotational joint comprising two first yoke uprights with a firstyoke axle disposed therebetween and a first hinge axle oriented at aright angle to said first yoke axle, said first yoke axle being coupledat a right angle to a first one of said controllable devices; providinga second rotational joint comprising two second yoke uprights with asecond yoke axle disposed therebetween and a second hinge axle orientedat a right angle to said second yoke axle, said second yoke axle beingcoupled at a right angle to a second one of said controllable devices;providing a cross-connection coupled between said first and second hingeaxles of said first and second rotational joints, said cross connectioncomprising a third hinge axle between said first and second hinge axlesand being adjustable to produce differential motion between said firstand second controllable devices; providing a self-aligning input pushrod assembly having a first end coupled to said cross connection at saidthird hinge axle between said first and second hinge axles, and a secondend configured for coupling to receive a single input control motion;and inducing said synchronous motion in said first and secondcontrollable devices in response to said single input control motionreceived at said third hinge axle of said cross connection; wherein saidsynchronous motion is induced by providing control motion to said firstcontrollable device through said first rotational joint, and providingcontrol motion to said second controllable device to said secondcontrollable device through said second rotational joint; wherein saidfirst hinge axle intersects said cross-connection at a first end of saidcross connection, said first hinge axle being disposed at a right angleto said cross connection; and wherein said second hinge axle intersectssaid cross-connection at a second end of said cross connection, saidsecond hinge axle being disposed at a right angle to said crossconnection.
 32. The method of claim 31, wherein said two adjacentcontrollable devices comprise adjacent control surfaces of an aircraft.33. The method of claim 31, wherein said two adjacent controllabledevices comprise dual elevator surfaces of a T-tail aircraft.